Former world number one Garbine Muguruza booked a semi final place at the Hong Kong Open Friday, fighting off a late comeback by Thailand's Luksika Kumkhum to win 6-2, 7-5.
Muguruza, the 2016 French Open and 2017 Wimbledon champion, is keen to finish what has been by her standards a disappointing season on a high.
She has slumped to a world ranking of 13, while her best Grand Slam performance was a semi final at Roland Garros.
The Spaniard was relieved to keep the hard-fought match to just two sets with a semi-final against world number five Elina Svitolina or China's leading player Wang Qiang looming Saturday.
"It was very competitive," the 25-year-old.
Kumkhum broke her as she served for the match, levelling the scores at 5-5, before Muguruza finally overcame her opponent, who is ranked 105.
"I feel in the second set she was playing so much better -- it was a full battle. I think the difference was a couple of points."
Earlier, China's Zhang Shuai looked in ominous form as she swatted aside last year's runner-up Daria Gavrilova in straight sets.
The world number 39 overwhelmed her Australian opponent -- who is ranked five places above her -- with the power and precision of her ground strokes and ran away with a comfortable 6-1, 6-3 victory after little more than an hour on court.
Zhang, China's number two, will make her debut in the Hong Kong semis Saturday when she takes on Ukrainian teenager Dayana Yastremska.
"The first and second rounds gave me a lot of confidence -- that's why today I played really well," Zhang, 29, said.
Last year's Hong Kong quarter finalist added she was happy soaking up the atmosphere on Centre Court.
"I'm really happy so many fans have come to Hong Kong. I'll try my best tomorrow!"
Gavrilova, 24, said she was tired after two three-set matches in the earlier rounds and said she suffered a painful knee during the pre-game warm-up which required heavy strapping.
But she said that was not why she lost. "I felt like she had her A-game today," Gavrilova said.
"I was dropping the ball too short and not finding the corners, I was getting myself into too much trouble by hitting the ball in the middle of the court really."
"I was feeling it and my legs were a bit tired but I'm kind of used to it and this wasn't the reason I lost."
Zhang, who has won two career WTA singles titles, will be favourite to win against 18-year-old Yastremska, currently ranked 102.
The 2016 Wimbledon girls singles finalist fought back from an early setback to win only her second WTA quarter-final earlier Friday.
The 18-year-old quickly went down 4-0 to outsider Kristina Kucova -- the world number 317 who knocked out Jelena Ostapenko in the first round -- before recovering to win 7-6 (8/6), 6-2.
"The crowds were supporting me so I felt that energy and I was very motivated to come back," she said.
Earlier this year, the big-serving teenager became the first player born this millennium to break into the WTA top 100 rankings.